Aqueous furfural vapor dye fixing



United States Patent 3,420,616 AQUEOUS FURFURAL VAPOR DYE FIXING Julian J. Hirshfeld, Egon H. Hacklander, and William H. Angevine, Jr., Decatur, Ala., assignors to Monsanto Company, St. Louis, Mo., a corporation of Delaware N0 Drawing. Filed July 29, 1965, Ser. No. 475,848 US. Cl. 8-55 17 Claims Int. Cl. D0611 3/00 This invention relates to a novel method for dyeing synthetic fibers, natural fibers, and combinations of synthetic and natural fibers. More specifically, the invention relates to a novel method wherein a dyeing assistant is used to fix the dyestufi in the fibers.

Dyeing, in the generic sense, consists essentially of placing a fiber into a dyestuff (usually an aqueous solution) and holding the fiber and the dyestufi in contact with each other for a sufiicient time at a sufficient temperature. Agents such as electrolytes, acids, carriers etc. may be present within the dyestufl? solution to promote dyeing. Take-up of the dye in the fiber is at a measurable rate until equilibrium is finally established with most of the dye absorbed on the fiber and a small part remaining in the dyestuff solution. The take-up rate of the dye in the fiber depends on each particular fiber and on the particular dyestuff; it is measured in percent take-up, e.g., a 100% take-up means that a 1 gram sample of fiber has absorbed 1 gram of dyestutf. In the early stages of dyeing a cross-section of the fiber shows ring dyeing and in the latter stages of dyeing, that is when equilibrium is almost obtained, a cross-section of the fiber shows that the dye has progressed from the ring or outer perimeter of the fiber to the core. The gaging of the dyeing through the cross-section of the fiber is measured in terms of penetration from 1 to 5, e.g., a penetration of 1 indicated the fiber is dyed only on the surface or outer perimeter of the fiber whereas a penetration of 5 indicated the fiber is dyed all the way through the cross-section of the fiber.

In order to obtain a satisfactory rate of dyeing with full penetration of the fibers it has been necessary to carry out the dyeing at high temperatures and/or at high pressures for a sufficient period of time. High-temperature dyeing has some advantages in that shorter dyeing times are realized, a full range of colors are possible on generally hydrophobic synthetic fibers without the use of costly carriers, and better levelling properties are obtained. However, disadvantages are associated with the high-temperature dyeing in that higher costs are usually experienced in such an installation, greater care is needed in the preparation of such a procedure, and certain dyestuffs and fibers are not stable at these high temperatures. The high temperature and high pressure dyeing systems generally have the same advantages and disadvantages but due to the high pressure of the system the cost of installation is usually compounded.

Pressure-dyeing methods are applicable with porous fabrics, loosely constructed fabrics. In this method pressure is used as a mover to push the dyestutt through the fabric. Tightly woven fabrics, e.g. nylon fabrics weighing 6 oz. per sq. yd., due to their close porosity can not be effectively dyed by this method. To overcome this disadvantage, high temperatures have been incorporated into the pressure-dyeing method; however, such a system still experiences difiiculty with fabrics that do not have a fairly open structure. Due to the high pressure required for these systems, installation and equipment costs are very high.

A number of methods have been proposed in the past for dyeing fibers, including synthetic fibers such as acrylic fibers, polyamides, polyesters and the like. However, many of these methods have turned out to be disadvantageous for a number of reasons. In many cases, the synthetic fibers dyed by these methods have proved to have poor light fastness and/or poor wash fastness. Other methods have resulted in altering the chemical characteristics of the fibers and thus have proved inafiective in dyeing fibers with desirable characteristics.

It is therefore an object of this invention to provide a novel method for dyeing synthetic fibers, natural fibers, and combinations of synthetic and natural fibers.

It is also an object of this invention to provide a novel, economical method for dyeing synthetic fibers, natural fibers, and combinations of synthetic and natural fibers. It is an object of this invention to provide a method for dyeing synthetic fibers which results in full penetration of the dyestufi in the fiber,

It is an object of this invention to provide a method for dyeing synthetic fibers with broad classes of dyestuif.

Another object of this invention is to provide a method for dyeing acrylic, polyamides, and polyester fibers with broad classes of dyestuff.

Still further, it is an object of this invention to provide a method for dyeing fibers of acrylic, polyamide, polyester, or blends of each with natural fibers in which the dyestutf fully penetrates the fibers resulting in good light fastness and wash fastness.

These and other objects of this invention are accomplished by providing a method of dyeing a fiber comprising contacting the fiber with a dyestutf then treating the fiber with vapors of water and furfural.

Fibers useful within this invention include synthetic fibers, natural fibers, and combinations of the two. For purposes of this invention, it is intended that synthetic fibers be defined as fibers made from natural polymers and fibers made from synthetic polymers.

Fibers made from natural polymers include rayon fibers, i.e., fibers composed of regenerated cellulose, and regenerated cellulose in which substituents have been added to replace not more than 15% of the hydrogens of the hydroxyl groups, and acetate fibers (fibers wherein the fiber-forming substance is cellulose acetate and not less than 92% of the hydroxyl groups are acetylated).

Fibers made from synthetic polymers include spandex (a fiber in which the fiber-forming substance is any longchain synthetic polymer composed of at least by weight of a segmented polyurethane), polyester (a fiber in which the fiber-forming substance is any long-chain synthetic polymer composed of at least 85% by weight of an ester of a dihydric alcohol and terephthalic acid), nylon [a fiber in which the fiber-forming substance is any long-chain synthetic polyamide having recurring amide groups as an integral part of the polymer chain], acrylic [a her in which the fiber-forming substance is any longchain synthetic polymer composed of at least 85% by Weight of acrylonitrile units and modacrylic [a fiber in which the fiber-forming substance is any long-chain synthetic polymer composed of less than 85 but at least 35% by weight of acrylonitrile units Nylon fabric examples include nylon 6 and nylon 6,6.

Natural fibers useful with this invention include cotton, wool, and silk. Blends of natural fibers and synthetic fibers are also useful in this invention. Examples of such blends include acrylic and cotton, acrylic and wool, nylon and cotton, polyester and silk, polyester and wool, polyester and cotton, e.g. 65% polyester and 35% cotton.

Vicara, a fiber made from maize protein, is also useful within the invention.

This invention is particularly applicable to fibers made from polyacrylonitrile and also to copolymers, interpolymers, and blends thereof, particularly blends containing at least 80% by weight of polymerized or copolymerized acrylonitrile. Such polymeric materials include acrylonitrile fiber-forming polymers with readily dyeable basic copolymers and to blends containing an overall polymerized acrylonitrile content of at least about 80% by weight. For example, the polymer may be a copolymer of from about 80% to about 98% of acrylonitrile and from about 2% to about 20% of another copolymerizable mono-olefinic monomer such as acrylic, alphachloroacrylic and methacrylic acids, the acrylates (e.g. methylmethacrylate, butylmethacrylate, methoxylmethylmethacrylate, beta-chloroethylmethacrylate, and the corresponding esters of acrylic and alpha-chloroacrylic acids), vinyl chloride, vinyl fluoride, vinyl bromide, vinylidene chloride, l-chloro-l-bromoethylene; methacrylonitrile; acrylamide and methacrylamide; alpha-chloroacrylamide, or monoalkyl substitution products thereof; methyl vinyl ketone; vanyl carboxylates, such as vinyl acetate, vinyl chloroacetate, vinyl propionate, and vinyl stearate; N- vinyl-imides, such as N-vinylphthalimide and N-vinylsuccinimide; methylene malonic ester; itaconic acid and itaconic ester; N-vinyl carbazole; vinyl furan; alkyl vinyl esters; vinyl sulfonic acid; ethylene alpha, beta-dicarboxylic acids or their anhydrides or derivatives thereof, such as diethylcitraconate, diethylmesaconate; styrene; vinyl naphthalene; vinyl-substituted tertiary heterocyclic amines such as the vinylpyridines and alkyl-substituted vinylpyridines, e.g., 2-vinylpyridine, 4-vinylpyridine, 2- rnethyl-S-vinylpyridine, and the like; l-vinylimidazole and alkyl-substituted l-vinylimidazoles, such as 2-, 4-, or 5- methyl-l-vinylimidazole, vinylpyrrolidone, vinylpiperidone, and other mono-olefinic copolymerizable monomeric materials.

The acrylic polymer can be a ternary interpolymer, e.g., products obtained by the interpolymerization of acrylonitrile and two or more of any of the above enumerated monomers, other than acrylonitrile. More specifically, and preferably, the ternary polymers can contain from about 80 to about 98 percent of acrylonitrile, from about 1 about percent of a vinylpyridine or l-vinylimid azole, and from about 1 to about 18 percent of another copolymerizable mono-olefinic substance, such as methacrylonitrile, vinyl acetate, methylmethacrylate, vinyl chloride, vinylidene chloride, and the like.

The acrylic polymer can also be a blend of polyacrylonitrile or of a copolymer of from about 80 to about 99 percent acrylonitrile and from about 1 to about 20 percent of at least one other mono-olefinic copolymerizable monomeric substance with from about 2 to about 50 percent of the weight of the blend of a copolymer of from about 30 to about 90 percent of a vinyl substituted tertiary heterocyclic amine and from about 10 to about 70 perc'nt of at least one other mono-olefinic copolymerizable monomer. When the polymeric material comprises a blend, preferably it will be a blend of from about 80 to about 99 percent of a copolymer of about 80 to about 98 percent acrylonitrile and from about 2 to about 20 percent of another mono-olefinic monomer, e.g., vinyl acetate, with from about 1 to about 20 percent of a copolymer of 'from about 30 to about 90 percent of a vinyl-substituted tertiary heterocyclic amine, such as vinyl pyridine, l-vinylimidazole, or a vinyl lactam, and from about 10 to about 70 percent of acrylonitrile to give a dyeable blend having an overall vinyl-substituted tertiary heterocyclic amine content of from about 2 to about 10 percent, based on the weight of the blend.

Polyamide fibers are also particularly applicable to this invention. These fibers are defined as linear polyamides formed by condensation of a diamine with a dibasic acid, by self-condensation of an amino acid or by a combina- 4 tion of both types. Examples of polyamides are disclosed in U.S. Patents 2,071,250, 2,071,253 and 2,130,948. Polyamide fibers can also be defined as polymers having recurring units of wherein R is hydrogen or a monovalent hydrocarbon radical and the average number of carbon atoms separating the amide groups is at least two. Specific examples of polyamide fibers include those obtained from polymers of tetramethylene diamine with adipic acid, tetramethylene diamine with suberic acid, tetramethylenediamine with sebacic acid, hexamethylenediamine with adipic acid, hexamethylenediamine with suberic acid, and hexamethylenediamine with sebacic acid. Also contemplated are polyamide fibers obtained from polymerization of two or more different diamines with a dicarboxylic acid or two or more different dicarboxylic acids with a diamine or two or more different dicarboxylic acids with two or more different diamines. Thus polyamide as used in this invention is defined to encompass the above.

Polyester fibers are also particularly applicable in this invention as are blends of polyesters and natural fibers, e.g. polyester and cotton, polyester and silk, and polyester and wool. Polyester fibers are defined as having a longchain synthetic polymer composed of at least by weight of an ester of a dihydric alcohol and terephthalic acid, e.g., terephthalic acid with ethylene glycol, dimethyl ester of terephthalic acid with ethylene glycol. Blends of 2 parts of polyester to 1 part of cotton are specifically applicable to this invention.

The dystuffs useful in this invention include all types of dyestuffs, e.g., acid dyestuffs, basic dyestuffs, direct dyestuffs, disperse dyestuffs, premetallized dyestuffs, etc. Particular fibers have an affinity to particular dyestuffs, it is therefore preferred that acid dyestuffs be used with acrylic, and polyamide; basic dyestuffs be used with acrylic, and silk; direct dyestuffs be used with cotton, polyamide, and silk; disperse dyestuffs be used with acetate, acrylic, polyester, and polyamide, and premetallized dyestuffs be used with acrylic, and polyamide. A list of useful dyestuffs can be found in Technical Manual of the American Association of Textile Chemists and Colorists, volume XXXVIII, 1962.

Application of the dyestuff on the fiber can be accomplished by many methods, e.g., by immersing the fiber in an aqueous solution of the dyestuff, by spraying the dyestuff on the fiber, by kiss rolling the dyestuff on the fiber, by padding the dyestuff on the fiber, etc. The dyestuff can be in an aqueous solution containing additives known to those people in the art, e.g., levelling agents such as cationic compounds, acids (formic acid, acetic acid, etc.), slightly alkaline salts (soda ash, sodium acetate, tetrasodium pyrophosphate, etc.), additives to adjust the viscosity and prevent migration of the dyestuff (a purified natural gum ether, sodium alginate, etc.) various surfactants, retarding agents, etc. It is understood as common knowledge within the art that certain additives are desired for certain dyestuffs.

After the fiber is contacted with the dyestuff, it is treated with vapors of water and furfural. This treatment fixes the dyestuff in the fiber and results in a dyed fiber having good wash fastness and color fastness. Before the fiber containing dyestuff is treated with the vapors of water and furfural, it is preferred that the fiber be heated to and maintained during the treatment at a temperature of from about F. to about 300 F. F. to about 250 being the preferred range) or that the fiber be dried, preferably at a temperature within the range of from about 212 F. to about 300 F. If the fiber is not dried or if it is maintained at a temperature below about 150 F., there is a possibility that furfural might form a resin cap on the fiber and prevent the dye from penetrating into the fiber.

The vapors of water and furfural should be within the range of from about 210 F. to about 250 F. At these temperatures, the concentration of furfural in water vapors should be within the range of from about 7% to about 515% by weight of furfural. Lower concentrations of furfural can be used, however, at lower concentrations full penetration of the dyestufi in the fiber may not be as effectively obtained. Also, if higher concentrations of furfural are used, erg. about 75%, there is a probability that some of the dyestuif on the fiber will be dissolved in the furfural. The concentration of furfural in the water vapors can be below the saturation point of the vapors, can be saturated in the water vapors, or it can be above the saturation point of the vapors (entrained in the water vapors). For example, a saturated solution of furfural in water at 50 F. has a composition of 8.3% furfural by weight in the solution and at the boil (208.8 F. and 760 mm.) a composition of 29.6% furfural by weight in the water vapors, and a saturated solution at 208.2" F. and 760 mm. has water vapors containing 35% furfural by weight. At higher temperatures, for example at 215 F. the water vapors can contain about 45% furfural by Weight. For purposes of this invention, it is preferred that the water vapors be saturated with furfural; however, entrained furfural in the water vapors and within the above concentrations are also preferred.

The treatment of the dyestufl" contacted fiber with vapors of water and furfural should be for a sutficient period of time and at a sufiicient temperature, i.e., from about 1 to about minutes and at a temperature of from about 210 F. to about 275 F., the perferred range being from about 205 F. to about 245 F. If the temperature of the vapors is at about 245 F. the period of time can be shorter, for example about 3 minutes; if the temperature of the vapors is at about 212 F. the period of time can be longer, about 7 minutes. A prolonged period of time at higher temperatures, i.e. in excess of 30 minutes at 250 P. will have a detrimental effect on the fiber.

There are many methods to generate the vapors of water and furfural, e.g., by maintaining a water and furfural mixture at its boiling point, introducing vaporized water (steam at different pressures) into the bottom of a body of furfural, etc. The methods can be adapted to a continuous dyeing system.

The following examples are presented to specifically illustrate the invention. These examples are not intended to limit in any way this invention but are presented to give a working knowledge of the same. It is to be understood also that the invention is not to be limited by the dyes disclosed, but any dye or combination of dyes which are useful on the synthetic fibers and the natural fibers may be used according to the invention with vapors of water and furfural. Examples I, IV, V, VI and VII illustrate the effectiveness of furfural and water vapors over water vapors exempt of furfural. All percents are by weight unless otherwise illustrated.

EXAMPLE I Swatches of polyester fiber and polyamide fiber were immersed for 0.5 second at room temperature with a dyestutf containing 20 grams per liter of Resolin Blue FBL paste (C.I. Disperse Blue 71), 160 grams per vliter of sodium alginate solution (2% chemical), and 820 grams of water, and then padded at 40 psi Half of the swatches were treated for 5 minutes with vapors emitted from a solution maintained at 212 F. and containing 200 cc. of furfnral in 2,000 cc. of water. The other half of the swatches were treated for 5 minutes with 212 F. vapors emitted from water. Both halfs were washed afterwards for 10 minutes at 160 F. in an aqueous solution containing 2 grams per liter of a non-ionic detergent (Igepal EXAMPLE II Swatches of acrylic carpet samples composed of 76.5% of a copolymer being 93% acrylonitrile and 7% vinyl acetate, 1 0.4% of a copolymer being 50% acrylonitrile and 50% methylvinyl pyridine and 13% of polyvinylchloride were sprayed with an aqueous dyestutf containing 1 gram per liter of Anthraquinone Blue SWT (C. I. Acid Blue 25 CJI. 62055), enough formic acid to adjust the pH to 2.0, and enough of a 20% solution of purified natural gum ether to adjust the viscosity to 175 op. The swatch was treated for 5 minutes with vapors emitted from a boiling aqueous solution containing 9% furfural. The swatch was treated for 5 minutes with vaporsni hou swatch showed a heavy shade of blue and, upon examining the fiber, a cross-section penetration of 4-5.

EXAMPLE III A swatch of acrylic carpet sample described in Example II was sprayed with an aqueous dyestuif containing 0.25 gram per liter of Calcozine Acrylic Red 3G (C.I. Basic Red 30), 0.25 gram per liter of Genacryl Blue 3G (Cl. Basic Yellow 28 Cl. 5 1005), enough soda ash to adjust the pH to 9.5 and enough of a 20% solution of a purified natural gum ether to adjust the viscosity to 175 cp. After treating the swatch for 5 minutes with vapors emitted from a boiling aqueous solution containing 9% furfural, it was observed that the sample had a heavy shade of color. Further examination of the fiber showed a cross-section penetration of 4-5.

EXAMPLE IV A sample of cotton was padded with an aqueous dyestuif solution containing 10 grams per liter of Pontamine Fast Yellow RL (CrI. Direct Yellow 50 CI. 29025) and grams per liter of sodium alginate. After drying, half the sample was treated for 5 minutes with atmospheric steam and the other half was treated for 5 minutes with atmospheric steam saturated with furfural. The sample treated with steam saturated with furfural showed 40% heavier shading than the sample treated with steam exempt of furfural.

EXAMPLE V The procedure of Example IV was repeated except the aqueous dyestutf solution contained 10 grams per liter of Diphenyl Fast Light Red 6 BF (C.I. Direct Red 30 CI. 35780) in place of Pontamine Fast Yellow RL. The sample treated with atmospheric steam saturated with furfural showed a shade 100% heavier in color than the sample treated with steam exempt of furfural.

EXAMPLE VI The procedure of Example IV was repeated except 10 grams per liter of Chlorantine Fast Blue 7GLL (C.I. Direct Blue 76 CI. 24410) was used in place of Pontamine Fast Yellow RL CJI. 29025. The sample treated with atmospheric steam saturated with furfur-al showed a shade 40% heavier in color than the sample treated with steam exempt of furfural.

EXAMPLE V II Two fiber samples each composed of 76.5 of a copolymer being 93% acrylonitrile and 7% vinyl acetate, 1 0.5% of a copolymer being 50% acrylonitrile and 50% methylvinyl pyridine, and 13% of polyvinylchloride, and sprayed with a dyestuff containing 1 gram per liter of Anthraquinone Blue SWF (C.I. Acid Blue 25 CI. 62055), enough formic acid to adjust the pH to 2, and enough of a 20% solution of purified natural gum ether to adjust the viscosity to 171 op. Dye pickup on the samples was 175%. One sample was treated for 5 minutes with atmospheric steam; the other sample was treated for minutes with vapors emitted from a boiling aqueous solution of 9% furfural. The fiber sample treated with atmospheric steam showed a penetration of 1 whereas the sample treated with the vapors of the boiling aqueous solution of 9% furfural showed a penetration of 4 to 5 and had a shade 50% heavier in color than the sample treated with atmospheric steam.

EXAMPLE VIII A fiber sample composed of 93% acrylonitrile and 7% vinyl acetate was padded at 140 F. with an aqueous dyestuff containing 10 grams per liter of Sevron Orange L (C.I. Basic Orange 24), 1 gram per liter of a purified natural gum ether (Polygum 260) and 0.5 gram per liter of a modified polyglycol ether (Tanapon X-70). The sample was heated at 240 F. for 5 minutes and was then treated for one minute with 212 F. steam saturated with furfural. Thereafter, the sample was rinsed cold, scoured for 10 minutes at the boil in an aqueous solution containing one gram per liter of a modified polyglycol ether (Tanapon X-70) and one gram per liter of tetrasodium pyrophosphate, and then dried. The fiber sample showed a deep shade of orange fast to washing and to crocking.

EXAMPLE IX A fiber sample composed of 93% acrylonitrile and 7% vinyl acetate was padded at 140 F. with an aqueous dyestuff containing 10 grams per liter of Basacryl Blue GL (C.-I. Basic Blue 54), 1 gram per liter of a purified natural gum ether Polygum 260), and 0.5 grams per liter of a modified polyglycol ether (Tanapon X-70). The sample was dried at 240 F. and treated for one minute with atmosphere steam saturated with furfural. Thereafter, the sample was rinsed cold, scoured 10 minutes at the boil in an aqueous solution containing one gram per liter of a modified polyglycol ether (Tanapon X-70) and one gram per liter of tetrasodium pyrophosphate, and then dried. A deep shade of blue fast to Washing and to crocking was observed on the sample.

EXAMPLE X A fiber sample composed of 93% acrylonitrile and 7% vinyl acetate was padded at 140 F. with an aqueous dyestuff containing 10 grams per liter of Maxilon Red BL (C.I. Basic Red 22), 1 gram per liter of a purified natural gum ether (Polygum 260), and 0.5 gram per liter of a modified polyglycol ether (Tanapon X-70). The sample was dried at 240 F. and then treated for 1 minute with atmospheric steam saturated with furfural. Thereafter, the sample was rinsed cold, scoured for 10 minutes at the boil in an aqueous solution containing 21 modified polyglycol ether (Tanapon X-70) and one gram per liter of tetrasodium pyrophosphate, and then dried. The sample showed a deep shade of red fast to washing and crocking.

EXAMPLE XI A fiber sample composed of 65% of a polyester obtained from the polymerization of tetrephthatic acid and ethylene glycol and of cotton was padded at 120 F. with an aqueous dyestuff containing 16 grams per liter of Latyl Blue LS 50% Paste (C.I. Disperse Blue 62), 1 gram per liter of sodium alginate and 0.5 gram per liter of a sodium alkylnaphthalene sulfonate (Nekal NF). The sample was dried at 240 1R, treated for one minute with atmospheric steam saturated with furfural, then scoured for 10 minutes at the boil in an aqueous solution containing one gram per liter of a non-ionic detergent and one gram per liter of tetrasodium pyrophosphate. After drying, the polyester fibers showed a medium shade of blue fast to washing and to crocking.

8 EXAMPLE XII The procedure of Example XI was repeated except the fiber sample was treated for five minutes with 212 F. steam saturated with furfural. The sample was observed to have a heavier shade of blue than Example XI fast to washing and to crocking.

EXAMPLE XIII A multi-fiber strip containing fiber samples of acrylic, polyamide, silk, vicara, and wool was padded at 120 F. with an aqueous dyestuff containing 5 grams per liter of Irgalan Yellow GL (C.I. Acid Yellow 114), a premetalized dyestulf. The strip was dried by maintaining it at 210 F. for 5 minutes. It was then treated for 5 minutes with vapors from a boiling aqueous solution containing 100 cc. per liter of furfural. Thereafter the strip was rinsed and scoured for 5 minutes at the boil in an aqueous solution containing 1 gram per liter of tetrasodium pyrophosphate and 1 gram per liter of a nonionic detergent. After the strip was rinsed and dried each of the fiber samples showed a good shade of yellow.

EXAMPLE X IV A multi-fiber strip containing fiber samples of acrylic, polyamide, and vicara was padded at 120 F. with an aqueous dyestufl containing 5 grams per liter of Brilliant Alizarine Milling Blue BL (Cl. Acid Blue O1. 61585), an acid dyestuff. The strip was dried at 210 F. and was then treated for 5 minutes with vapors from a boiling solution containing cc. per liter of furfural in water. Thereafter, the strip was rinsed and scoured for 5 minutes at the boil in an aqueous solution containing 1 gram per liter of tetrasodium pyrophosphate and 1 gram per liter of a non-ionic detergent. After rinsing and drying all the fiber samples showed a deep shade of blue.

EXAMPLE XV A multi-fiber strip containing fiber samples of acrylic, silk, and vicara was padded at F. with an aqueous dyestuif containing 5 grams per liter of Sevron 'Red GL (C.I. Basic Red 18), a basic dyestuff. The strip was dried at 210 F. and was then treated for 5 minutes with vapors emitted from an aqueous boiling solution containing 100 cc. per liter of furfural. The strip was rinsed and scoured for 5 minutes at the boil with an aqueous solution containing 1 gram per liter of tetrasodium pyrophosphate and 1 gram per liter of a non-ionic detergent. After rinsing and drying the strip, all the fiber samples showed a deep shade of red.

EXAMPLE XVI A multi-fiber strip containing fiber samples of acrylic, cotton, polyamide, silk, and vicara was padded at 120 F. with an aqueous dyestuif containing 5 grams per liter of Direct Fast Yelow BWP (CI. Direct Yellow 28 CI. 19155), a direct dyestuff. After the strip was dried at 210 F., it was treated for 5 minutes with vapors from a boiling solution contaning 100 cc. per liter of furfural in water. Thereafter the strip was rinsed and scoured for 5 minutes at the boil in an aqueous solution containing 1 gram per liter of tetrasodium pyrophosphate and 1 gram per liter of a non-ionic detergent. After the strip was rinsed and dried all the fiber samples showed a deep shade of yellow.

EXAMPLE XV I-I liter of a non-ionic detergent. After the strip was rinsed and dried, all the fiber samples showed a deep shade of red.

What is claimed is:

1. A method of dyeing a fiber comprising contacting the fiber with a dyestuff then treating the fiber with vapors of water and furfural.

2. The method of claim 1 wherein the fiber is synthetic fiber.

3. The method of claim 1 wherein the fiber is a natural fiber.

4. The method of claim 1 wherein the fiber is a blend of a synthetic fiber and a natural fiber.

5. The method of claim 1 wherein the dyestuff is selected from the group consisting of acid dyestuffs, basic dyestuffs, dispersed dyestuffs, direct dyestuffs, and premetalized dyestuffs.

6. The method of claim 1 wherein the vapors of water and furfural are at a temperature within the range of from about 205 F. to about 212 F.

7. The method of claim 1 wherein the vapors of water and furfur' al have a concentration of from about 7.5% to about 55% by Weight of furfural.

8. A method of dyeing a fiber selected from the class consisting of synthetic fibers, natural fibers, and combinations of a-synthetic fiber and a natural fiber comprising contacting the fiber with a dyestuff selected from the class consisting of acid dyestuffs, basic dyestuffs, dispersed dyestuffs, direct dyestuffs, and premetalized dyestuffs, heating to and maintaining the fiber at a temperature of from 175 F. to about 300 F., then treating the fiber with vapors from a boiling aqueous mixture of furfural and water, the concentration of furfural being at about 7.5 to about 45 %'by weight.

9. The method of claim 8 wherein the fiber is a polyacrylonitrile fiber.

10. The method of claim 8 wherein the fiber is a polyamide fiber.

11. The method of claim 8 wherein the fiber is a polyester fiber.

12. The method of claim 8 wherein the fiber is a blend of polyester fiber and cotton fiber.

13. The method of claim 8 wherein the vapors of water and furfural are at a temperature of from about 205 F. to about 212 F.

14. A method of dyeing a fiber selected from the class consisting of polyacrylonitrile fiber, polyamide fiber, and polyester fiber comprising contacting the fiber with a dyestuff selected from the class consisting of acid dyestuffs,

basic dyestuffs, dispersed dyestuffs, direct dyestuffs and premetalized dyestuffs, heating to and maintaining the fiber at a temperature of from about to about 300 F., then treating the fiber with vapors of water saturated with furfural at a temperature of from about 205 F. to about 212 F.

15. A method of dyeing a fabric comprising contacting the fabric with a dye'stuff and then treating the fabric with vapors of water and lfurfural.

16. A method of dyeing a fabric comprised of fibers selected from the class, consisting of synthetic fibers, natural fibers, and combinations of synthetic: fibers and natural fibers, comprising the steps of contacting the fabric with a dyestuff selected from the class consisting of acid dyestuffs, basic dyestuffs, dispersed dyestuffsg direct dyestuffs, and pre-metallized dyestuffs; heating to and maintaining the fabric at a temperature of from about 175 F. to about 300 F.; then treating the fabric with vapors from a boiling aqueous mixture of furfuralfland water, the concentration of furfural being at about 7.5% to about 45% by weight. i

17. A method of dyeing a fabric compris d of fibers selected from the class consisting of acrylic fibers, polyamide fibers, and polyester fibers comprising the steps of contacting the fabric with a dyestutf selected from the class consisting of acid dyestuffs, basic dyestuffs, dispersed dyestuffs, direct dyestuffs and pre-metallized dyestuffs; heating to and maintaining the fabric at a temperature of from about 175 F. to about 300 F then treating the fabric with vapors of water saturated with furfural at a temperature of from aboiit 205 F. to about 212 F.

References Cited UNITED STATES PATENTS 1,760,076 5/1960 Miner 8-l2 2,174,005 9/1939 Miller 8-93 XR 3,353,900 11/1967 Hirshfeld et a1 8-93 XR OTHER REFERENCES Spiel, Textile Chemistry and Auxiliaries, chapter 7, pp. 167*169', 174, 175, 179 and 182-184, pub. 1957 by Reinhold Pub. Corp., New York.

NORMAN G. TORCHIN, Primary Examiner. D. LEVY, Assistant Examiner.

U.S. Cl. X.R. 854, 93, 54.2

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pa-iient No. 3,420,616 January 7, 1969 Julian J. Hirshfeld et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 19, cancel "swatch was treated for 5 minutes with vaporsni hou". Column 7 line 36 "atmosphere" should read atmospheric I Signed and sealed this 21st day of April 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents 

1. A METHOD OF DYEING A FIBER COMPRISING CONTACTING THE FIBER WITH A DYESTUFF THEN TREATING THE FIBER WITH VAPORS OF WATER AND FURFURAL. 